Temperature-dependent structural changes on DDAB surfactant assemblies evidenced by energy dispersive X-ray...

Area of Science:

• Materials Science
• Biophysics
• Nanotechnology

Background:

• Cationic amphiphile DDAB forms biomembrane mimics and DNA delivery vehicles.
• Optimizing DDAB vector properties requires understanding their thermotropic behavior.
• Non-viral gene delivery systems benefit from tunable physicochemical properties.

Purpose of the Study:

• Investigate the thermotropic mesophase structure of silicon-supported DDAB thin films.
• Analyze the thermotropic behavior of DDAB and DDAB/DOPC water-dispersed vesicles.
• Correlate structural changes with potential applications in gene delivery.

Main Methods:

• Energy Dispersive X-ray Diffraction (EDXD) for silicon-supported films.
• Dynamic Light Scattering (DLS) for water-dispersed vesicles.
• Varying temperature and relative humidity to study structural transitions.

Main Results:

• DDAB films thin significantly above 55 °C.
• DDAB-water vesicles show reduced size polydispersity with increasing temperature.
• A humidity-dependent gel-crystalline mesophase forms upon cooling DDAB films.
• DDAB/DOPC vesicles exhibit temperature-dependent size distribution switching.

Conclusions:

• DDAB assemblies display distinct thermotropic and structural responses.
• The observed phase transitions are relevant for designing optimized DNA vectors.
• Temperature-induced changes in DDAB/DOPC vesicles suggest potential biomedical applications.